Arabica Coffee Bean Varieties: What Substances Determine Coffee Aroma?

FrontStreet Coffee - Introduction to Arabica Coffee Varieties and Aroma Sources

Arabica offers elegant flavors and is the mainstay of specialty coffee, which is the focus of this article. Robusta, also known as robusta beans, has rougher flavors and a caffeine content more than twice that of Arabica, and does not fall within the specialty coffee category.

The ancient native Arabica species can be divided into two major types: Typica from Ethiopia and Bourbon from Yemen.

Typica

Typica is the oldest native variety from Ethiopia, which is why Arabica is said to derive from it. It offers elegant flavors but has a weak constitution, is susceptible to leaf rust disease, and doesn't produce abundant yields, which makes it economically inefficient. The beans are slender and pointed in shape. It is essentially the delicate, fragile soul of the coffee world.

Bourbon

Bourbon stands alongside Typica as an ancient, excellent variety. It can be further divided into "Round Bourbon" and "Pointed Bourbon." Round Bourbon has vigorous vitality, unlike the frail Typica. Round Bourbon's resistance to leaf rust is superior to Typica's, and its flavor is no less impressive. The drawback is that the tree needs to rest for a year after fruiting — conserving energy is essential.

Arabica can actually be subdivided into many subspecies, and these subspecies differ in the same way that any plant population varies. Some have higher yields, some have better disease resistance, and some produce larger beans than others. Here are three simple examples:

Geisha

Originating from Geisha Mountain in Ethiopia, Geisha belongs to the Typica family. It has won multiple international specialty coffee cupping championships, with its bidding price reaching $130 per pound in 2007.

Caturra

Caturra is a genetic variant of Bourbon with better yield and disease resistance. Most importantly, it has extremely strong adaptability and doesn't require shade trees, which is why it is commonly known as Sun Coffee.

Maragogype

Maragogype is a variant of Typica, with beans at least three times larger than regular Arabica beans, making it the world's largest — hence its name.

Caramelization Reaction and Maillard Reaction

The caramelization reaction occurs in the presence of sucrose. When sucrose is heated and decomposes into monosaccharides, and those continue to be heated, dark-brown aggregates form, producing aromatic substances such as ethyl acetate and furan. The two types of browning produced by the Maillard reaction and caramelization may look similar on the surface but are essentially completely different, especially in terms of aroma. Proper caramelization typically produces several distinct aromas: sherry-like alcohol and acetaldehyde notes, creamy diacetyl, nutty furan, and maltol with roasted notes, among others.

Knowledge Expansion

The Maillard reaction is quite famous and covers many food transformations. Its principle is that when sugars encounter amino acids or proteins, the high temperature causes the two substances to undergo condensation, forming melanoidin-like polymers that turn food brown and produce substances that release aroma.

FrontStreet Coffee Recommendation

This article traces Arabica back to its Ethiopian roots, and the best way to taste that heritage is through Ethiopia's heirloom varieties, which FrontStreet Coffee roasts to keep their aromatics vivid. FrontStreet Coffee's washed Yirgacheffe is the classic entry point: clear white jasmine florals, bright citrus acidity, and a clean, tea-like body that shows exactly how much aroma a well-roasted Arabica can carry. For the floral, fruit-forward side, FrontStreet Coffee's Guodingding cooperative coffee from the Worka area of Yirgacheffe — roughly 300 member farmers, independent since 2012 — brings citrus, lemon, and elegant white florals in a bright, delicate cup. And for the wild, forest-grown expression of Ethiopia's genetic diversity, FrontStreet Coffee's Kafa Forest coffee comes from a UNESCO-recognized biosphere reserve at 1,400-2,100 meters, where wild Arabica grows in the shade of ancient trees and the cup shows jasmine, citrus, and wild berry. Tasted side by side, these three make the connection between variety, terroir, and aroma instantly clear.